It is known that polyureas possess a number of considerable advantages over polyurethanes of corresponding structure. Polyureas are obtained by reaction of polyisocyanates with polyamines. Suitable polyamines are particularly polyether polyamines of higher molecular weight. According to German Offenlegungsschrift No. 2 019 432, polyamines suitable for the production of such polyureas are obtained from aliphatic polyether polyols and isatic acid anhydride.
It was found that the use of polyether diamines having one of several heterocyclic nuclei (rings) in their molecule (center) leads to the obtention of polyureas which are far superior to those known in respect of thermal stability and tensile and structural strength.
The invention relates to novel compounds having terminal amino groups, said novel compounds being of the general formula ##STR1## wherein z is 2 or 3, X stands for oxygen or sulfur and R is a z-valent group of the formula ##STR2## wherein k is 1 or 2, A stands for alkylidene or alkylated or non-alkylated vinylene, y stands for B when k=1 and z=2, for--CH.sub.2 --when k=2 and z=2 and for ##STR3## when k=2 and z=3, and B in each case represents a divalent polyalkylene ether group or a polyalkylene thioether group such as it is obtained by removal of the hydroxyl or mercapto group from a polyalkylene ether diol or a polyalkylene thioether dithiol of a molecular weight of 100 up to 15000. A further object of the invention is to provide a process for the production of these compounds. The production of the compounds of the present invention is advantageously effected by heating of a compound of the general formula (HX).sub.z R (general formula III) wherein z is 2 or 3 and R and X have the meaning defined above with at least z equivalents of isatic acid anhydride in the presence of strong bases to temperatures of 30.degree. to 150.degree. C., perferably to temperatures of 45.degree. to 130.degree. C. The reaction can be carried out with or without the presence of inert solvents. The amount of catalyst used can be varied within a wide range. Preferably, 1 to 10 parts by weight of the alkaline compound per 100 parts by weight of isatic acid anhydride are employed. The reaction is completed as soon as gas development ceases. The catalyst and excess isatic acid anhydride are filtered off, optionally after addition of an inert solvent, and the final product is obtained with a high degree of purity after treatment with CO.sub.2, shaking with water and drying in vacuo under stirring. For the majority of application purposes, simple filtration of the amino polyether under pressure suffices.
Suitable starting materials for the process according to the invention are polyether diols and polyether triols as well as polythioether dithiols and polythioether triols and diols, triols, dithiols and trithiols comprising polyether segments or polythioether segments.
In the event that diols or dithiols (z=2) are used as starting materials in the process of the present invention, these could be chosen among the polyether diols or polythioether dithiols of the formula III having a molecular weight of about 100 to 15000, preferably 500 to 10000, in particular 500 to 3000, which are obtained by reaction of tetrahydrofurane or tetrahydrofurane and ethylene oxide or tetrahydrofurane and propylene oxide with a compound corresponding to the group R in formula II wherein B is hydrogen, CH.sub.2 CH.sub.2 OH or CH.sub.2 CH(CH.sub.3)OH.
Preferred in the process according to the invention is the use of polymerisates of the formula III which are obtained by reacting ethylene oxide or propylene oxide or other 1,2-alkylene oxides or ethylene oxide and propylene oxide with a compound corresponding to R in formula II wherein B is hydrogen, CH.sub.2 CH.sub.2 OH or CH.sub.2 CH(CH.sub.3)OH.
These compounds are produced according to conventional processes such as disclosed in German Offenlegungsschrift No. 2,003,016. Particularly preferred examples of the new compounds of the formula I obtained according to the process of the invention and having terminal amino groups are the following: ##STR4##
In these formulae of preferred compounds of the formula I, m, n and o in each case represent such integers that molecular weights of about 500 to about 15000, preferably of about 500 to about 3000 (when using diols or dithiols) and of about 800 to about 15000 (when employing triols or trithiols) are obtained in the compounds of the formula I.
In detail, compounds of the general formula I, their production and application are preferred in which A stands for an alkylidene group of 1 to 6 carbon atoms. Particularly obtainable among these are compounds of the formula I wherein A represents an isopropylidene group, an ethylidene group or a methyl vinylene group. B in the formula I can have the meaning of a polyethylene ether group, a polypropylene ether group or a polyalkylene ether group comprising ethylene ether groups and propylene ether groups in any given sequence.
The polyalkylene ether group can further contain ether groups as well as thioether groups.
Particularly preferred because of the ready availability of the starting materials and the properties of the end products are compounds of the formula I wherein B stands for a polyalkylene ether group derived from tetrahydrofurane, a polyalkylene ether group containing ethylene ether groups and alkylene ether groups derived from tetrahydrofurane in any given sequence or for a polyalkylene ether group containing alkylene ether groups derived from tetrahydrofurane and propylene ether groups, in any given sequence.
In the production of the new compounds of the formula I according to the present invention, it is thus preferred to use compounds of the general formula III wherein R represents a group of the formula II wherein A and/or B have one of the preferred meanings indicated above.
A further object of the present invention is the use or application of the compounds according to the invention or obtainable according to the process of the invention as reactants with polyisocyanate in the production of plastic materials according to the isocyanate polyaddition process.
The production of plastic materials from the new compounds according to the invention in the isocyanate polyaddition process can be effected in any given manner conventional in polyurethane chemistry, i.e. employed in the reaction of polyhydroxyl compounds with polyisocyanates. This means that the reaction of the new compounds with polyisocyanates can be carried out in the presence of all the additives known in polyurethane chemistry, such as catalysts, flame-retarding substances and the like.
In the production of elastomeric plastic materials of high modulus of elasticity, the polyadducts have preferably been obtained up to now in the presence of low molecular aromatic diamines as chain extenders. Since these diamines are carcinogenic, their use is encountering objections of a physiological nature. When employing the compounds according to the invention, the use of low molecular aromatic diamines can be completely omitted in the production of elastomeric plastic materials of high modulus of elasticity.
Suitable polyisocyanates for the production of polyadducts employing the new compounds of the present invention are all polyisocyanates known in polyurethane chemistry, such as, for instance, tetramethylene diisocyanate, hexamethylene diisocyanate, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, mixtures of these isomers, 4,4-diisocyanato diphenyl methane or the like.
As already mentioned, the polyadducts produced employing the new compounds according to the invention possess considerable advantages over polyurethanes of corresponding structure, particularly due to the increase in elasticity, stability and thermal stability.